Global mapping of the yeast genetic interaction network

A genetic interaction network containing approximately 1000 genes and approximately 4000 interactions was mapped by crossing mutations in 132 different query genes into a set of approximately 4700 viable gene yeast deletion mutants and scoring the double mutant progeny for fitness defects. Network connectivity was predictive of function because interactions often occurred among functionally related genes, and similar patterns of interactions tended to identify components of the same pathway. The genetic network exhibited dense local neighborhoods; therefore, the position of a gene on a partially mapped network is predictive of other genetic interactions. Because digenic interactions are common in yeast, similar networks may underlie the complex genetics associated with inherited phenotypes in other organisms.     

A B cell-based sensor for rapid identification of pathogens

We report the use of genetically engineered cells in a pathogen identification sensor. This sensor uses B lymphocytes that have been engineered to emit light within seconds of exposure to specific bacteria and viruses. We demonstrated rapid screening of relevant samples and identification of a variety of pathogens at very low levels. Because of its speed, sensitivity, and specificity, this pathogen identification technology could prove useful for medical diagnostics, biowarfare defense, food- and water-quality monitoring, and other applications.     

Oral Salmonella typhimurium vaccine expressing circumsporozoite protein protects against malaria

Immunization with radiation-attenuated malaria sporozoites induces potent cellular immune responses, but the target antigens are unknown and have not previously been elicited by subunit vaccines prepared from the circumsporozoite (CS) protein. A method is described here for inducing protective cell-mediated immunity to sporozoites by immunization with attenuated Salmonella typhimurium transformed with the Plasmodium berghei CS gene. These transformants constitutively express CS antigens and, when used to immunize mice orally, colonize the liver, induce antigen-specific cell-mediated immunity, and protect mice against sporozoite challenge in the absence of antisporozoite antibodies. These data indicate that the CS protein contains T cell epitopes capable of inducing protective cell-mediated immunity, and emphasize the importance of proper antigen presentation in generating this response. Analogous, orally administered vaccines against human malaria might be feasible.     

Homology of retractile filaments of vampire squid

The axial filament nerves of Vampyroteuthis infernalis are joined to two separate parts of the brain. One branch of the nerve, apparently efferent, arises from the anterior portion of the middle subesophageal mass, and the other, apparently afferent. enters the ventral magnocellular lobe. Since this innervation is entirely different from that of the arms, the filaments can no longer be considered homologous with the arms. The validity and primitive nature of the order Vampyromorpha, therefore, needs to be reexamined.     

Efficient tandem polymer solar cells fabricated by all-solution processing

Tandem solar cells, in which two solar cells with different absorption characteristics are linked to use a wider range of the solar spectrum, were fabricated with each layer processed from solution with the use of bulk heterojunction materials comprising semiconducting polymers and fullerene derivatives. A transparent titanium oxide (TiO(x)) layer separates and connects the front cell and the back cell. The TiO(x) layer serves as an electron transport and collecting layer for the first cell and as a stable foundation that enables the fabrication of the second cell to complete the tandem cell architecture. We use an inverted structure with the low band-gap polymer-fullerene composite as the charge-separating layer in the front cell and the high band-gap polymer composite as that in the back cell. Power-conversion efficiencies of more than 6% were achieved at illuminations of 200 milliwatts per square centimeter.     

Carbohydrate supply as a regulator of rat liver phosphoenolpyruvate carboxykinase activity

Administration of glucose, fructose, and glycerol to fasted rats produced a significant depression of liver phosphoenolpyruvate carboxykinase activity within 4 to 8 hours; galactose and ribose were much less effective. All the compounds yielded appreciable quantities of liver glycogen. The depression of phosphoenolpyruvate carboxykinase activity by glucose and glycerol was diminished by the concomitant administration of 2-deoxyglucose. The latter depressed glycogen formation from administered carbohydrate in muscle but not in liver. In rats made diabetic by alloxan, depression of elevated phosphoenolpyruvate carboxykinase activity by insulin was dependent upon a dietary source of carbohydrate. These results were interpreted to indicate that depression of certain gluconeogenic enzymes after carbohydrate ingestion is initiated by the metabolism of carbohydrate in some extrahepatic site.     

Nerve growth factor: relationship to the cyclic AMP system of sensory ganglia

Nerve growth factor and N(6),O(2)' dibutyryl adenosine 3',5'-monophosphate both stimulate neurite elongation by explanted ganglia. However, the addition of nerve growth factor does not lead to increased amounts of adenosine 3',5'-monophosphate in intact ganglia, nor does it stimulate adenylate cyclase activity in broken ganglia cells.